On Mon, Jan 11, 2021 at 09:30:55PM +0900, Stafford Horne wrote:
> On Thu, Jan 07, 2021 at 04:04:47AM +0800, kernel test robot wrote:
> > Hi Pawel,
> >
> > FYI, the error/warning still remains.
> >
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > master
> > head: e71ba9452f0b5b2e8dc8aa5445198cd9214a6a62
> > commit: 22447a99c97e353bde8f90c2353873f27681d57c drivers/soc/litex: add
> > LiteX SoC Controller driver
> > date: 8 weeks ago
> > config: x86_64-randconfig-a001-20210107 (attached as .config)
> > compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project
> > 5c951623bc8965fa1e89660f2f5f4a2944e4981a)
> > reproduce (this is a W=1 build):
> > wget
> > https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
> > ~/bin/make.cross
> > chmod +x ~/bin/make.cross
> > # install x86_64 cross compiling tool for clang build
> > # apt-get install binutils-x86-64-linux-gnu
> > #
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=22447a99c97e353bde8f90c2353873f27681d57c
> > git remote add linus
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > git fetch --no-tags linus master
> > git checkout 22447a99c97e353bde8f90c2353873f27681d57c
> > # save the attached .config to linux build tree
> > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross
> > ARCH=x86_64
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <[email protected]>
> >
> > All warnings (new ones prefixed by >>):
> >
> > >> drivers/soc/litex/litex_soc_ctrl.c:143:34: warning: unused variable
> > >> 'litex_soc_ctrl_of_match' [-Wunused-const-variable]
> > static const struct of_device_id litex_soc_ctrl_of_match[] = {
> > ^
> > 1 warning generated.
> >
> >
> > vim +/litex_soc_ctrl_of_match +143 drivers/soc/litex/litex_soc_ctrl.c
> >
> > 142
> > > 143 static const struct of_device_id litex_soc_ctrl_of_match[] = {
> > 144 {.compatible = "litex,soc-controller"},
> > 145 {},
> > 146 };
> > 147
> >
>
> I don't use clang but GCC, and I cannot reproduce this warning.
>
> $ make drivers/soc/litex/litex_soc_ctrl.o
> CALL scripts/checksyscalls.sh
> CALL scripts/atomic/check-atomics.sh
> DESCEND objtool
> CC drivers/soc/litex/litex_soc_ctrl.o
>
> Also, I can see litex_soc_ctrl_of_match is used. I am not sure what is going
> on
> here.
>
> -Stafford
>
You need W=1
$ make -skj"$(nproc)" W=1 olddefconfig drivers/soc/litex/litex_soc_ctrl.o
drivers/soc/litex/litex_soc_ctrl.c:143:34: warning: ‘litex_soc_ctrl_of_match’
defined but not used [-Wunused-const-variable=]
143 | static const struct of_device_id litex_soc_ctrl_of_match[] = {
| ^~~~~~~~~~~~~~~~~~~~~~~
$ rg "CONFIG_OF|CONFIG_LITEX_SOC_CONTROLLER" .config
1124:# CONFIG_OF is not set
4673:CONFIG_LITEX_SOC_CONTROLLER=y
This variable is used in two places in that file, in the
MODULE_DEVICE_TABLE macro and the of_match_ptr macro. When CONFIG_OF is
disabled, of_match_ptr evaluates to NULL. When the file is built into
the kernel image, MODULE_DEVICE_TABLE evaluates to nothing, leaving this
variable defined but unused in the final preprocessed source.
Hope that helps!
Cheers,
Nathan
